#include<unistd.h>
#include<fcntl.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<stdlib.h>
#include<stdio.h>
#include<linux/soundcard.h>
 
#define Audio_Device "/dev/snd/pcmC0D0p"
 
//不同的声音有着不同的播放参数，这些参数可以使用file命令获得
 
#define Sample_Size 16 //there're two kinds of bits,8 bits and 16 bits
#define Sample_Rate 8000 //sampling rate
 
int play_sound(const char *filename){
    struct stat stat_buf;
    unsigned char * buf = NULL;
    int handler,fd;
    int result;
    int arg,status;
    
    //打开声音文件，将文件读入内存
    fd=open(filename,O_RDONLY);
    if(fd<0) return -1;
    if(fstat(fd,&stat_buf)){
        close(fd);
        return -1;
    }
 
    if(!stat_buf.st_size){
        close(fd);
        return -1;
   }
   buf=(unsigned char *)malloc(stat_buf.st_size);
   if(!buf){
      close(fd);
      return -1;
   }
 
   if(read(fd,buf,stat_buf.st_size)<0){
      free(buf);
      close(fd);
      return -1;
   }
 
   //打开声卡设备，并设置声卡播放参数，这些参数必须与声音文件参数一致
   handler=open(Audio_Device,O_WRONLY);
   if(handler==-1){
       perror("open Audio_Device fail");
       return -1;
   }
   
   arg=Sample_Rate;
   status=ioctl(handler,SOUND_PCM_WRITE_RATE,&arg);
   if(status==-1){
      perror("error from SOUND_PCM_WRITE_RATE ioctl");
      return -1;
   }
 
   arg=Sample_Size;
   status=ioctl(handler,SOUND_PCM_WRITE_BITS,&arg);
   if(status==-1){
      perror("error from SOUND_PCM_WRITE_BITS ioctl");
      return -1;
   }
   
   result=write(handler,buf,stat_buf.st_size);
   if(result==-1){
      perror("Fail to play the sound!");
      return -1;
   }
 
   free(buf);
   close(fd);
   close(handler);
   return result;
}
 
int main(int argc, char* argv[])
{
   return play_sound("air.wav");
}
